Langmuir-Blodgett films precursors

Kim, J.H., et al. 1995. Preparation and characterization of poly(p-phenylene vinylene) Langmuir-Blodgett film formed via precursor method. Synth Met 71 2023. 

The second motivation of the recent development of oligothiophenes is related to their use as materials for electronic device applications. As early as 1974, a precursor article by H. Kuhn et al. [13] describes photocurrent measurements on Langmuir-Blodgett films of a-quinquethiophene (a-5T). In the mid-1980s, oligothiophenes... 

The systems that we study are monolayers of phospholipids and fatty acids at air/water interfaces. This interface is physically very interesting since it enables a high degree of freedom to vary many parameters. On the other hand films manipulated at the water surface are also the precursors of Langmuir-Blodgett films, i.e. mono- or multilayers of these lipids on solid support. Phase transitions in these systems, which are also of technical relevance, will be discussed at the end of the second part. 

Here, we demonstrate that oriented PAV films with well-developed -conjugated system can be fabricated through the regulation of orientation of precursor polymer chains by use of the Langmuir-Blodgett technique, and that large and anisotropic third-order optical nonlinearity was observed in the oriented PAV films. 

The dotted line on the left is a bond in a possible precursor trimer. X-ray data suggest an area of 21 3 per alkyl chain, with a thickness of 25 2 A. FTIR spectroscopy suggest that the alkyl chains in -octadecyltrichlorosi-lane SAMs are perpendicular to the surface (Reprinted with permission from [5] A. Ul-man, Introduction to Thin Organic Films From Langmuir-Blodgett to Self Assembly, Academic Press, Boston, 1991. p. 257 and 258. Copyright 1991 Academic Press/Elsevier Science)... 

Mono- and multilayer films of polyimides were successfully prepared using Langmuir-Blodgett technique. Monolayer films of polyamic acid long alkylamine salts were prepared at the air-water interface. The mono-layer films were deposited on appropriate plates to produce multilayer films of the precursor to polyimide films. Finaly, the polyimide multilayer films were obtained by treatment of the multilayer films of the polyamic acid amine salts with acetic anhydride and pyridine. The polyimide multilayer films had excellent coating ability giving a very smooth surface. They also exhibited insulating characteristics as reliable as polyimide thick films. 

The precursor polymer can be fabricated, e.g., by spin-coating, dipcoating or by Langmuir-Blodgett techniques into thin films. The pyro-... 

The precursor polymer can be fabricated, e.g., by spin-coating, dip-coating, or by Langmuir-Blodgett techniques into thin films. The pyrolysis of the materials is performed in high vacuum at temperatures of 180-300 °C for 12 h. In the final step, hydrogen chloride and tetrahydrothiophene will be removed. 

Hagting J G, Vorenkamp E J and Schouten A J (1998) Dipping induced orientation in Langmuir-Blodgett multilayers of a flexible PPV precursor polymer, Thin Solid Films 327 65-68. 

In PPV films deposited onto silver substrate, parallel chainlike features were reported, with larger separation (typically 1.8 nm) than expected from the interchain unit cell [132]. This was observed independently of polymer film thickness and material used as substrate and was tentative attributed to some surface reconstruction, possibly due to adsorption of oxygen. Polarization-dependent photoabsorption measurements made in PPV mono-layers prepared by the Langmuir-Blodgett precursor technique onto Mo 2 substrate showed that the phenylene and vinylene moieties are nearly parallel to the surface [125]. 

Langmuir-Blodgett (LB) films have been formed from PPV precursor polymers. Kim et al. [123] deposited the methoxy precursor to PPV (3, Scheme 11) by this method and converted it to PPV by thermal treatment at 300 C. Regular STM features were observed, indicating that a high degree of order was obtained both before and after conversion. The photoluminescence (PL) spectrum was blue-shifted from normal, which was... 

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